Calculators
The arithmetic from the explainers, as working tools.
Kelly Criterion Calculator
Calculator Bankroll and Kelly staking Kelly sizes a bet to maximise long-run growth. It is optimal only if your probability esti…
Expected Value Calculator
Calculator Expected value calculator Expected value is the average result of a bet repeated indefinitely. It is exact arithmetic…
Implied Probability Calculator
Calculator Implied probability and break-even win rate Every price states a win rate. This page tells you what that rate is, and…
Odds Converter
Calculator Odds converter American, decimal, fractional and implied probability are four ways of writing the same price. Enter a…
Vig Calculator
Calculator Vig, hold and the no-vig fair line Add up the implied probabilities of every side of a market. Whatever it exceeds 10…
Parlay Calculator
Calculator Parlay calculator A parlay multiplies prices, which also multiplies margins. This page shows both the payout and what…
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How a price is built
A betting price is a probability with a fee on top. These pages take that apart in order.
Staking and risk
Sizing a bet, surviving variance, and the part that is about you rather than the market.